A crutch (also known as a mobility aid) is an important tool for assisting the elderly, persons with an injured leg, the physically handicapped and mountaineers (hereinafter collectively referred to as the users) in standing and walking, mainly by providing support to the users to therefore lessen the burden borne by the users' legs.
Depending on how they operate, conventional crutches generally fall into two categories, namely forearm crutches (underpinned by the users' hands) and underarm crutches (underpinned by the users' armpits.) A grip is disposed at the top of the forearm crutch and held by the user's hand while the user is standing or walking. An axillary support is disposed at the top of the underarm crutch and underpinned by the user's armpit while the user is standing or walking.
The bottom ends of the conventional forearm crutches and underarm crutches each come in the form of a single leg or four legs. To reduce the ground reaction force exerted by the ground on the crutches in contact with the ground and provide an anti-skid function, the bottom ends of the crutches are usually fitted to crutch tips (typically made of rubber.) Since the crutch tips are resilient, the users holding and resting on the crutches in contact with the ground experience less vibration than they will when the crutch tips are not resilient. In addition, the crutch tips which are resilient can increase the friction between the ground and the bottom ends of the crutches and thus provide an anti-skid function.
However, in some circumstances, for example, at night or in dim surroundings, conventional crutches fail to give any alert or provide any illumination, and in consequence the users are exposed to danger.